The answer is, I am emulating “Pitch Drift” of the classic analog synthesizer using LFOs on the waveform level. I used a technique derived from this great article from Sound On Sound magazine.

…And now for something completely different. For my friend Arfy, here is a little remix from an old Casio toy keyboard. I don’t remember the model at the moment. Other then the arrangement of the loops and the fact that I layer them sometimes, they are exactly as you would hear from the instrument itself.

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